The present invention generally relates to a pointing device for controlling a pointer or cursor in a display, such as a computer monitor screen, and in particular to an optical pointing device selectively operable in forward moving mode and rearward moving mode.
Pointing devices are widely used in computer systems and a variety of electronic devices for moving a cursor or pointer shown on a display to control/operate for example pull-down menu bars and selective actuation of certain functions of the electronic device. Examples of the pointing devices include computer mice, joysticks, tracking balls and touch pads. Most of the conventional pointing devices are operated mechanically, such as moving a part relative to another part and applying pressure to certain parts.
The conventional mechanical pointing devices require conversion of mechanical signals into optical signal which are then further converted into electrical signals to be transferred to an associated computer system. For example, a computer mouse or a tracking ball comprises a rolling sphere which is mechanically rotated when the computer mouse or tracking ball is in operation. The rotation of the sphere is converted into optical signals by an optical encoding system. The optical signal is then processed by a transducer to generate a corresponding electrical signal. This not only increases costs of the pointing devices, but also complicates the operation thereof. Sensitivity of the pointing devices in picking up signals may also be adversely affected by such a complicated structure, especially by the mechanical parts thereof.
It is thus desirable to provide a pointing device to alleviate the above mentioned problems.
Accordingly, an object of the present invention is to provide a pointing device comprising no moving parts for simplifying the structure and operation thereof and reducing costs of manufacturing and maintenance.
Another object of the present invention is to provide a pointing device operable in both forward moving mode and rearward moving mode.
A further object of the present invention is to provide an optical pointing device which generates optical signals and optical signals are converted into electrical signals directly with no mechanical signal required.
To achieve the above objects, in accordance with the present invention, there is provided an optical pointing device comprising a base which can be for example a casing of a computer mouse. The base defines a cavity having an opening in a surface of the base. An optical sensing system is received and retained in the cavity. The optical sensing system comprises a lens located in front of the optical sensing system for directing optical signals toward/away from the optical sensing system. A light-transmitting panel is removably and selectively mounted to the opening of the cavity for covering the cavity. The distance between the panel and the lens is substantially equal to the focusing length of the lens whereby an object moving on the panel can be clearly detected by the optical sensing system and then converted into a corresponding first electrical signal to drive the cursor in a first direction. The pointing device can be placed on a fixed surface with the panel removed and moved with respect to the fixed surface for generating a second electrical signal to drive the cursor in an opposite second direction. A panel detection element is mounted in the body for detecting the presence of the panel and serves as a switch for switching the pointing device between forward moving mode where the first electrical signal is generated and rearward moving mode where the second electrical signal is generated.